With the Mandalorian threat looming very real, Vanquo became part of a Republic security cordon known as the Jebble-Vanquo-Tarnith line. Designed to defend Taris, the line was host to heavy, stalemated fighting on worlds like Suurja[7]—however, in 3964 BBY, all this changed. At Taris' Jedi Tower, four of the five Padawans undergoing training as the next generation of Jedi on the planet were murdered, supposedly by the lone surviving classmate, Zayne Carrick. After Carrick escaped pursuit and fled the planet, public confidence in the Jedi Order was severely shaken, leading to the Jedi High Council withdrawing the five Jedi Masters stationed at the Jedi Tower back to Coruscant. Mandalore the Ultimate took this as a signal to begin his attack, launching a three-pronged offensive aimed at seizing Taris. The real Mandalorian Wars had begun.[5]

"It's working, Mand'alor. The Republic fleet's left flank has split to cover Vanquo—clearing the way for our main thrust!""Then the path to Taris is clear, at last."

―Cassus Fett and Mandalore the Ultimate discuss their attack on Vanquo[src]

The space battle above Vanquo

Mandalore intended all along for the attack on Vanquo to be a diversion, meant to draw the Republic fleet's left flank and open the way for the Mandalorians' main thrust toward Taris. To that end, the Mandalorians landed in force on the nightside of the planet, led by CommanderRohlan Dyre, who had been in trouble for desertion on several previous occasions. The shock infantry touched down among the mining camps that dotted Vanquo's mountainous landscape,[5] many dropping down on Basilisk war droids and scout speeders as well as Meteor-class Q-Carriers and Shaadlar-type troopships—at one outpost, a Mandalorian force, including Dyre himself, happened across the fugitive Zayne Carrick and his friends, who had previously faked a Mandalorian attack on the outpost to clear it for scavenging. The group was caught by surprise, and the Arkanian OffshootJarael, who had been posing as a Jedi in their previous con, was taken prisoner on a Teroch-type gunship. As the others attempted to escape, Dyre used the commotion as a cover to escape the battle in the group's ship, the Last Resort.[3] Carrick's group caught up to Dyre as he was flying toward orbit, with the Last Resort under heavy Mandalorian blaster fire. However, Dyre succeeded in flying the Last Resort out of the Vanquo battle zone.[5]

Not only did the Mandalorian conquest of Vanquo give the Neo-Crusaders a stronghold on the Rim that they would not relinquish, but the battle also helped set the stage for the Mandalorians' attack on Taris shortly afterward.[8] The Jebble-Vanquo-Tarnith line broken, Republic Admiral Jimas Veltraa reformed the remnants of the Outer Rim fleets into a line to defend Taris.[2] However, the Mandalorians still captured Taris,[4] with Veltraa perishing in the destruction of his flagship, the Reliance. Saul Karath's strong defense of and fighting retreat from Vanquo proved to be a career-maker for the captain, as he was promoted to admiral after the battle was over.[2]